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Sangwoo Kang, Kwang Deok Shin, Jeong Hun Kim, Taijoon Chung
Using quantitative assays for autophagy, we analyzed 4 classes of atg mutants, discovered new atg2 phenotypes and ATG gene interactions, and proposed a model of autophagosome formation in plants. Plant and other eukaryotic cells use autophagy to target cytoplasmic constituents for degradation in the vacuole. Autophagy is regulated and executed by a conserved set of proteins called autophagy-related (ATG). In Arabidopsis, several groups of ATG proteins have been characterized using genetic approaches. However, the genetic interactions between ATG genes have not been established and the relationship between different ATG groups in plants remains unclear...
April 2018: Plant Cell Reports
Liming Luo, Pingping Zhang, Ruihai Zhu, Jing Fu, Jing Su, Jing Zheng, Ziyue Wang, Dan Wang, Qingqiu Gong
Salinity stress challenges agriculture and food security globally. Upon salt stress, plant growth slows down, nutrients are recycled, osmolytes are produced, and reallocation of Na(+) takes place. Since autophagy is a high-throughput degradation pathway that contributes to nutrient remobilization in plants, we explored the involvement of autophagic flux in salt stress response of Arabidopsis with various approaches. Confocal microscopy of GFP-ATG8a in transgenic Arabidopsis showed that autophagosome formation is induced shortly after salt treatment...
2017: Frontiers in Plant Science
Jing-Xiang Zheng, Yan Li, Yue-He Ding, Jun-Jie Liu, Mei-Jun Zhang, Meng-Qiu Dong, Hong-Wei Wang, Li Yu
PtdIns3P signaling is critical for dynamic membrane remodeling during autophagosome formation. Proteins in the Atg18/WIPI family are PtdIns3P-binding effectors which can form complexes with proteins in the Atg2 family, and both families are essential for macroautophagy/autophagy. However, little is known about the biophysical properties and biological functions of the Atg2-Atg18/WIPI complex as a whole. Here, we demonstrate that an ortholog of yeast Atg18, mammalian WDR45/WIPI4 has a stronger binding capacity for mammalian ATG2A or ATG2B than the other 3 WIPIs...
2017: Autophagy
Eri Hirata, Yoshikazu Ohya, Kuninori Suzuki
Autophagy, an intracellular degradation system, is highly conserved among eukaryotes from yeast to mammalian cells. In the yeast Saccharomyces cerevisiae, most Atg (autophagy-related) proteins, which are essential for autophagosome formation, are recruited to a restricted region close to the vacuole, termed the vacuole-isolation membrane contact site (VICS), upon induction of autophagy. Subsequently, the isolation membrane (IM) expands and sequesters cytoplasmic materials to become a closed autophagosome. In S...
2017: PloS One
Daniela Bakula, Amelie J Müller, Theresia Zuleger, Zsuzsanna Takacs, Mirita Franz-Wachtel, Ann-Katrin Thost, Daniel Brigger, Mario P Tschan, Tancred Frickey, Horst Robenek, Boris Macek, Tassula Proikas-Cezanne
Autophagy is controlled by AMPK and mTOR, both of which associate with ULK1 and control the production of phosphatidylinositol 3-phosphate (PtdIns3P), a prerequisite for autophagosome formation. Here we report that WIPI3 and WIPI4 scaffold the signal control of autophagy upstream of PtdIns3P production and have a role in the PtdIns3P effector function of WIPI1-WIPI2 at nascent autophagosomes. In response to LKB1-mediated AMPK stimulation, WIPI4-ATG2 is released from a WIPI4-ATG2/AMPK-ULK1 complex and translocates to nascent autophagosomes, controlling their size, to which WIPI3, in complex with FIP200, also contributes...
May 31, 2017: Nature Communications
Claire B Péan, Mark Schiebler, Sharon W S Tan, Jessica A Sharrock, Katrin Kierdorf, Karen P Brown, M Charlotte Maserumule, Shinelle Menezes, Martina Pilátová, Kévin Bronda, Pierre Guermonprez, Brian M Stramer, R Andres Floto, Marc S Dionne
Mycobacterium tuberculosis remains a global threat to human health, yet the molecular mechanisms regulating immunity remain poorly understood. Cytokines can promote or inhibit mycobacterial survival inside macrophages and the underlying mechanisms represent potential targets for host-directed therapies. Here we show that cytokine-STAT signalling promotes mycobacterial survival within macrophages by deregulating lipid droplets via ATG2 repression. In Drosophila infected with Mycobacterium marinum, mycobacterium-induced STAT activity triggered by unpaired-family cytokines reduces Atg2 expression, permitting deregulation of lipid droplets...
March 6, 2017: Nature Communications
Jérôme Cornillon, Marie Balsat, Aurélie Cabrespine, Emmanuelle Tavernier-Tardy, Eric Hermet, Aurélien Mulliez, Karine Augeul-Meunier, Denis Guyotat, Jacques-Olivier Bay
Reduced intensity conditioning for allogeneic hematopoietic stem cell transplantation (allo-HSCT) is often proposed for patients with comorbidities. To enhance engraftment and limit graft-versus-host disease (GVHD), antithymoglobulin (ATG) is usually used. However, the dose needed remains unclear unlike myeloablative conditioning. In order to clarify this point, we conducted a retrospective study on patients who received a reduced intensity conditioning allo-HSCT based on a 2-day fludarabine and busulfan treatment with either 1 or 2 days of ATG treatment...
2016: Acta Haematologica
Joanna Kaminska, Weronika Rzepnikowska, Anna Polak, Krzysztof Flis, Piotr Soczewka, Katarzyna Bala, Marzena Sienko, Marcin Grynberg, Pawel Kaliszewski, Agnieszka Urbanek, Kathryn Ayscough, Teresa Zoladek
Human Nedd4 ubiquitin ligase, or its variants, inhibit yeast cell growth by disturbing the actin cytoskeleton organization and dynamics, and lead to an increase in levels of ubiquitinated proteins. In a screen for multicopy suppressors which rescue growth of yeast cells producing Nedd4 ligase with an inactive WW4 domain (Nedd4w4), we identified a fragment of ATG2 gene encoding part of the Atg2 core autophagy protein. Expression of the Atg2-C1 fragment (aa 1074-1447) improved growth, actin cytoskeleton organization, but did not significantly change the levels of ubiquitinated proteins in these cells...
October 2016: International Journal of Biochemistry & Cell Biology
Dah-Shyong Yu, Chia-Lun Wu, Szu-Yuan Ping, Cheng Keng, Kun-Hung Shen
Immunotherapy using bacille Calmette-Guerin (BCG) instillation is the mainstay treatment modality for superficial urothelial cancer (UC) through toll-like receptor (TLR) activation of cognitive immune response. We investigated the roles of TLR7 in the activation of apoptosis in UC cells after BCG treatment. The in vitro cytotoxicity effect of BCG on UC cells was measured by a modified 3-(4,5-dimethylthiazo-2-yl)-2,5-diphenyl tetrazolium assay. Expressions of TLR7 mRNA and protein in native UC cells prior to and after BCG treatment were analyzed using real-time quantitative polymerase chain reaction and western blot methods...
August 2015: Kaohsiung Journal of Medical Sciences
Y Zhang, R Cai, R Zhou, Y Li, L Liu
Programmed cell death (PCD) has an important role in sculpting organisms during development. However, much remains to be learned about the molecular mechanism of PCD. We found that ectopic expression of tousled-like kinase (tlk) in Drosophila initiated a new type of cell death. Furthermore, the TLK-induced cell death is likely to be independent of the canonical caspase pathway and other known caspase-independent pathways. Genetically, atg2 RNAi could rescue the TLK-induced cell death, and this function of atg2 was likely distinct from its role in autophagy...
January 2016: Cell Death and Differentiation
Sandra Muñoz-Braceras, Rosa Calvo, Ricardo Escalante
Deficient autophagy causes a distinct phenotype in Dictyostelium discoideum, characterized by the formation of multitips at the mound stage. This led us to analyze autophagy in a number of multitipped mutants described previously (tipA(-), tipB(-), tipC(-), and tipD(-)). We found a clear autophagic dysfunction in tipC(-) and tipD(-) while the others showed no defects. tipD codes for a homolog of Atg16, which confirms the role of this protein in Dictyostelium autophagy and validates our approach. The tipC-encoded protein is highly similar to human VPS13A (also known as chorein), whose mutations cause the chorea-acanthocytosis syndrome...
2015: Autophagy
Simon G Pfisterer, Daniela Bakula, Alice Cezanne, Horst Robenek, Tassula Proikas-Cezanne
Macroautophagy (autophagy hereafter) is an evolutionarily highly conserved catabolic process activated by eukaryotes in order to counteract cellular starvation. Autophagy leads to bulk degradation of cytoplasmic content in the lysosomal compartment, thereby clearing the cytoplasm and generating nutrients and energy. Upon autophagy initiation, cytoplasmic material becomes sequestered in newly formed double-membrane vesicles termed 'autophagosomes' that subsequently acquire acidic hydrolases for content destruction...
October 2014: Biochemical Society Transactions
Kwang Deok Shin, Han Nim Lee, Taijoon Chung
Autophagy targets cytoplasmic cargo to a lytic compartment for degradation. Autophagy-related (Atg) proteins, including the transmembrane protein Atg9, are involved in different steps of autophagy in yeast and mammalian cells. Functional classification of core Atg proteins in plants has not been clearly confirmed, partly because of the limited availability of reliable assays for monitoring autophagic flux. By using proUBQ10-GFP-ATG8a as an autophagic marker, we showed that autophagic flux is reduced but not completely compromised in Arabidopsis thaliana atg9 mutants...
May 2014: Molecules and Cells
S P Chantepie, A C Gac, O Reman
In reduced-toxicity conditioning hematopoietic stem cell transplantation, several studies failed to demonstrate the superiority of one conditioning over another. This study described 51 patients (median age of 58 years) allografted with the new FB3-ATG2 conditioning regimen for myeloid (66%) or lymphoid disease (33%). Comorbidity index ≥3 was noted in 23.5% of patients. Toxicities were close to those observed with RIC. One-year cumulative incidence of acute and chronic GVHD was 18.9% and 39.2%. The 2-year-NRM, DFS and OS were 25%, 57...
May 2014: Leukemia Research
Altaf Mohammed, Naveena B Janakiram, Misty Brewer, Rebekah L Ritchie, Anuj Marya, Stan Lightfoot, Vernon E Steele, Chinthalapally V Rao
Epidemiologic studies have shown that diabetes mellitus is associated positively with increased risk of pancreatic ductal adenocarcinoma (PDAC), and recent meta-analysis studies showed that metformin, reduces the risk of pancreatic cancer (PC). We tested the effects of metformin on pancreatic intraepithelial neoplasia (PanIN) and their progression to PDAC in p48Cre/+.LSL-KrasG12D/+ transgenic mice. Mice fed control diet showed 80% and 62% incidence of PDAC in males and females, respectively. Male mice showed 20% and 26%, and female mice showed 7% and 0% PDAC incidence with 1000- and 2000-ppm metformin treatments, respectively...
December 1, 2013: Translational Oncology
Dayana E Salas-Leiva, Alan W Meerow, Javier Francisco-Ortega, Michael Calonje, M Patrick Griffith, Dennis W Stevenson, Kyoko Nakamura
Several individuals of the Caribbean Zamia clade and other cycad genera were used to identify single-copy nuclear genes for phylogeographic and phylogenetic studies in Cycadales. Two strategies were employed to select target loci: (i) a tblastX search of Arabidopsis conserved ortholog sequence (COS) set and (ii) a tblastX search of Arabidopsis-Populus-Vitis-Oryza Shared Single-Copy genes (APVO SSC) against the EST Zamia databases in GenBank. From the first strategy, 30 loci were selected, and from the second, 16 loci...
July 2014: Molecular Ecology Resources
Péter Nagy, Krisztina Hegedűs, Karolina Pircs, Ágnes Varga, Gábor Juhász
The Atg2-Atg18 complex acts in parallel to Atg8 and regulates Atg9 recycling from phagophore assembly site (PAS) during autophagy in yeast. Here we show that in Drosophila, both Atg9 and Atg18 are required for Atg8a puncta formation, unlike Atg2. Selective autophagic degradation of ubiquitinated proteins is mediated by Ref(2)P/p62. The transmembrane protein Atg9 accumulates on refractory to Sigma P (Ref(2)P) aggregates in Atg7, Atg8a and Atg2 mutants. No accumulation of Atg9 is seen on Ref(2)P in cells lacking Atg18 or Vps34 lipid kinase function, while the Atg1 complex subunit FIP200 is recruited...
January 31, 2014: FEBS Letters
Michitaro Shibata, Kazusato Oikawa, Kohki Yoshimoto, Maki Kondo, Shoji Mano, Kenji Yamada, Makoto Hayashi, Wataru Sakamoto, Yoshinori Ohsumi, Mikio Nishimura
The positioning of peroxisomes in a cell is a regulated process that is closely associated with their functions. Using this feature of the peroxisomal positioning as a criterion, we identified three Arabidopsis thaliana mutants (peroxisome unusual positioning1 [peup1], peup2, and peup4) that contain aggregated peroxisomes. We found that the PEUP1, PEUP2, and PEUP4 were identical to Autophagy-related2 (ATG2), ATG18a, and ATG7, respectively, which are involved in the autophagic system. The number of peroxisomes was increased and the peroxisomal proteins were highly accumulated in the peup1 mutant, suggesting that peroxisome degradation by autophagy (pexophagy) is deficient in the peup1 mutant...
December 2013: Plant Cell
Thomas Hackenberg, Trine Juul, Aija Auzina, Sonia Gwizdz, Anna Malolepszy, Katrien Van Der Kelen, Svend Dam, Simon Bressendorff, Andrea Lorentzen, Peter Roepstorff, Kåre Lehmann Nielsen, Jan-Elo Jørgensen, Daniel Hofius, Frank Van Breusegem, Morten Petersen, Stig Uggerhøj Andersen
Programmed cell death often depends on generation of reactive oxygen species, which can be detoxified by antioxidative enzymes, including catalases. We previously isolated catalase-deficient mutants (cat2) in a screen for resistance to hydroxyurea-induced cell death. Here, we identify an Arabidopsis thaliana hydroxyurea-resistant autophagy mutant, atg2, which also shows reduced sensitivity to cell death triggered by the bacterial effector avrRpm1. To test if catalase deficiency likewise affected both hydroxyurea and avrRpm1 sensitivity, we selected mutants with extremely low catalase activities and showed that they carried mutations in a gene that we named NO CATALASE ACTIVITY1 (NCA1)...
November 2013: Plant Cell
Lisa M Farmer, Mauro A Rinaldi, Pierce G Young, Charles H Danan, Sarah E Burkhart, Bonnie Bartel
Peroxisomes house critical metabolic reactions that are essential for seedling development. As seedlings mature, metabolic requirements change, and peroxisomal contents are remodeled. The resident peroxisomal protease LON2 is positioned to degrade obsolete or damaged peroxisomal proteins, but data supporting such a role in plants have remained elusive. Arabidopsis thaliana lon2 mutants display defects in peroxisomal metabolism and matrix protein import but appear to degrade matrix proteins normally. To elucidate LON2 functions, we executed a forward-genetic screen for lon2 suppressors, which revealed multiple mutations in key autophagy genes...
October 2013: Plant Cell
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